Replaces `std::shared_pointer` with `stx::atomic_ptr` and `stx::shared_ptr`.
Notes to programmers:
* This pr kills the use of `dynamic_cast`, `std::dynamic_pointer_cast` and `std::weak_ptr` on IDM objects, possible replacement is to save the object ID on the base object, then use idm::check/get_unlocked to the destination type via the saved ID which may be null. Null pointer check is how you can tell type mismatch (as dynamic cast) or object destruction (as weak_ptr locking).
* Double-inheritance on IDM objects should be used with care, `stx::shared_ptr` does not support constant-evaluated pointer offsetting to parent/child type.
* `idm::check/get_unlocked` can now be used anywhere.
Misc fixes:
* Fixes some segfaults with RPCN with interaction with IDM.
* Fix deadlocks in access violation handler due locking recursion.
* Fixes race condition in process exit-spawn on memory containers read.
* Fix bug that theoretically can prevent RPCS3 from booting - fix `id_manager::typeinfo` comparison to compare members instead of `memcmp` which can fail spuriously on padding bytes.
* Ensure all IDM inherited types of base, either has `id_base` or `id_type` defined locally, this allows to make getters such as `idm::get_unlocked<lv2_socket, lv2_socket_raw>()` which were broken before. (requires save-states invalidation)
* Removes broken operator[] overload of `stx::shared_ptr` and `stx::single_ptr` for non-array types.
* Make vm::unmap atomic, squash the memory unmapping process inside this function while still using the same VM mutex ownership.
* Make vm::unmap not fail due to random vm::get calls, shared_ptr reference count is no longer a condition.
* Fix sys_mmapper_free_address spuriously failing with EBUSY due to random vm::get calls.
* Fix sys_vm_unmap race condition due to non-atomic vm::unmap.
* Add an optional verification block ptr arg to vm::unmap, used by patches.
This reverts commit 4599d58413.
The issue this works around was fixed in 3265772 ("idm: Implement
creation/destruction invalidation counter") by making the variables
constexpr.
Fixes#6896
